The present disclosure relates generally to coupling devices for connecting two fluid-carrying conduits in end-to-end relation, as between a fluid source and fluid-utilizing device. More particularly, the present disclosure relates to a thermally sensitive fluid coupling for automatic disconnection in the event the coupling is exposed to temperatures above a predetermined temperature.
Thermally sensitive couplings are often used to releasably join fluid-carrying conduits, such as gas lines or the like. These quick-disconnect couplings are typically designed with a heat sensitive element that allows the coupled sections of the gas lines to disconnect automatically when the coupling is exposed to temperatures above a predetermined temperature. Disconnection of the fluid-carrying conduits triggers an interruption in the fluid flow path. The interruption of the fluid flow path halts the flow of flammable material (for example, natural or liquefied petroleum (LP) gas) to the heat source.
On type of fluid coupling includes a threaded connecting sleeve, which has a heat sensitive portion at one end and normally functions to connect the components of the fluid delivery system. A limitation of such a design is that the plastic used for the rotatable sleeve can have a sensitivity to certain commonly used cleaning chemicals and/or other agents which may be used to detect gas leakage. In addition, this type of coupling is rendered totally unusable when it thermally releases, because the heat sensitive portion is integrated with the connecting sleeve itself.
Another type of fluid coupling comprises a plug body which is held in a socket chamber by an annular collar. In turn, the collar is held on the plug body by a separate annular ring of fusible material which, when exposed to a predetermined excessive temperature, releases the plug body to shut off fluid communication in the fluid delivery system. Although such two-piece systems can be desirable because they are versatile, the construction of some of these systems is such that the independent fusible element often is not strong enough to counter the spring force exerted thereon even at normal temperatures, and thus may not prevent axial movement of the plug body over time. Further, such a coupling is often not adapted for ready assembly.
Accordingly, there is a need for a thermally responsive fluid coupling which incorporates an independent component that is sensitive to heat, adapted to retain a conventional fluid-carrying section without modification of the coupling components, and may be readily assembled.